Photoresist compositions and methods

ABSTRACT

New photoresist and topcoat compositions are provided that are useful in a variety of applications. In one aspect, new photoresist compositions are provided that comprise: (a) a first matrix polymer; (b) one or more acid generators; and (c) one or more additive compounds of Formulae (I) and/or (II).

CROSS-REFERENCE TO RELATED APPLICATION

This Application claims the benefit of U.S. Provisional Application62/612,582 filed on Dec. 31, 2017, which is incorporated herein byreference in its entirety.

BACKGROUND

The invention relates generally to the manufacture of electronicdevices. More specifically, this invention relates to photoresist andtopcoat compositions and to photolithographic processes which allow forthe formation of fine patterns. Compositions of the invention areparticularly useful in immersion lithography processes for the formationof semiconductor devices.

Photoresists are photosensitive films used for the transfer of images toa substrate. A coating layer of a photoresist is formed on a substrateand the photoresist layer is then exposed through a photomask to asource of activating radiation. Following exposure, the photoresist isdeveloped to provide a relief image that permits selective processing ofa substrate.

Considerable effort has been made to extend the practical resolutioncapabilities of positive tone resist development, including in immersionlithography. One such example involves negative tone development (NTD)of a traditionally positive-type chemically amplified photoresistthrough use of particular developers, typically organic developers suchas ketones, esters or ethers, leaving behind a pattern created by theinsoluble exposed regions. See, for instance, U.S. Pat. No. 6,790,579.

Certain additives have been employed to attempt to improve resistresolution. See JPH11337722A; US2007190451; EP1702962B1; US20060172149;US20130177853; US20130344436; US20140038102; U.S. Pat. No. 6,132,931;US20120077120; U.S. Pat. Nos. 6,391,521; 9,563,123.

In immersion lithography, direct contact between the immersion fluid andphotoresist layer can result in leaching of components of thephotoresist into the immersion fluid. This leaching can causecontamination of the optical lens and bring about a change in theeffective refractive index and transmission properties of the immersionfluid. In an effort to ameliorate this problem, use of a topcoat layerover the photoresist layer as a harrier between the immersion fluid andunderlying photoresist layer has been proposed. The use of topcoatlayers in immersion lithography, however, presents various challenges.Topcoat layers can affect, for example, the process window, criticaldimension (CD) variation and resist profile depending on characteristicssuch as topcoat refractive index, thickness, acidity, chemicalinteraction with the resist and soaking time. In addition, use of atopcoat layer can negatively impact device yield due, for example, tomicro-bridging defects which prevent proper resist pattern formation.

To improve performance of topcoat materials, the use of self-segregatingtopcoat compositions to form a graded topcoat layer has been proposed,for example, in Self-segregating Materials for Immersion Lithography,Daniel P. Sanders et al, Advances in Resist Materials and ProcessingTechnology XXV, Proceedings of the SPIE, Vol 6923, pp.692309-1-692309-12 (2008). See also US20120264053.

Electronic device manufacturers continually seek increased resolution ofa patterned photoresist image. It would be desirable to have newcompositions that could provide enhanced imaging capabilities.

SUMMARY

We now provide new compositions that are useful in photolithographicapplications, including immersion lithography processes.

In preferred embodiments, the present compositions can exhibit enhancedshelf-life, including comparatively decreased degradation of acomposition upon extended storage. See, for instance, the comparativedata set forth in the Examples which follow.

More particularly, in a first aspect, photoresist compositions areprovided that comprise: (a) a first matrix polymer; (b) one or more acidgenerators; and (c) one or more additive compounds having a structure ofthe following Formulae (I) or (II):

wherein in each of those Formulae (I) and (2) R₁ and R₂ are each thesame or different non-hydrogen substituent such as optionallysubstituted alkyl, optionally substituted alkoxy, optionally substitutedthioalkyl, optionally substituted carbocyclic aryl or an optionallysubstituted heteroaromatic group,

or R₁ or R₂ can be connected via a group Z where Z is a single bond or agroup selected from C═O; S(O); S(O)₂; —C(═O)O—; —C(═O)NH—;—C(═O)—C(═O)—; —O—; CHOH; CH₂; S; —B—;

-   -   X in each formulae is one of the following:

wherein R₃ is a non-hydrogen substituent; and

each n is a positive integer of 1 to 5. Preferred optional substitutionof R₁ and R₂ include for example substitution by —OY—NO₂, —CF₃—;—C(═O)NHY; —C(═O)—C(═O)—Y; CHOY; CH₂Y; —SY; —B(Y)n; —NHC(═O)Y; —(C═O)OY(with Y being a linear or branched, saturated or unsaturated alkylgroup, a fluoro alkane or alkene or alkyne, or carbocyclic aryl orheteroaromatic).

In preferred aspects, the photoresist composition will contain a secondpolymer distinct from the first polymer. Preferably, such a secondpolymer will comprise fluoro substitution such as one or morefluoroC₁₋₁₂alkyl groups. In particular aspects, the second polymer maycomprise a repeat unit of the following Formula (3):

wherein in Formula (3) R₄ and R₅ are each independently a hydrogen, ahalogen, a C₁₋₈alkyl, or C₁₋₈haloalkyl group such as fluoroC₁₋₈alkyl,and L is an optionally substituted multivalent linking group such as—(CH₂)q- where q is 1, 2, 3, 4, 5, or 6.

In preferred aspects, the additive compound comprises one or moreanhydride moieties. Preferred additive compounds also may be halogenatedparticularly fluorinated. Preferred additive compounds also may comprisea sulfonic acid ester group.

In a further aspect, topcoat compositions for use over a photoresistlayer are provided, Preferred topcoat compositions may comprise (a) afirst matrix polymer; (b) a second polymer distinct from the firstpolymer; and (c) one or more additive compounds having a structure ofthe following Formulae (I) or (II):

wherein in each of those Formulae (I) and (2), R₁, R₂ X, and R₃ and nare the same as defined above.

Preferably, the second polymer of a topcoat composition will comprisefluoro substitution such as one or more fluoroC₁₋₁₂alkyl groups. Inparticular aspects, the second polymer may comprise a repeat unit of thefollowing Formula (3):

wherein in Formula (3) R₄ and R₅ are each independently a hydrogen, ahalogen, a C₁₋₈alkyl, or C₁₋₈haloalkyl group such as fluoroC₁₋₈alkyl,and L is an optionally substituted multivalent linking group such as—(CH₂)q- where q is 1, 2, 3, 4, 5, or 6.

In preferred aspects, the additive compound comprises one or moreanhydride moieties. Preferred additive compounds also may be halogenatedparticularly fluorinated. Preferred additive compounds also may comprisea sulfonic acid ester group.

According to a further aspect, coated substrates are provided. Thecoated substrates comprise a substrate and a layer of a photoresistcomposition of the invention over a surface of the substrate. Coatedsubstrates also are provided that comprise a substrate and a layer of atopcoat composition of the invention.

The topcoat composition typically will be coated over a photoresistcomposition layer, which may be a photoresist composition of theinvention.

According to a yet further aspect, methods of forming aphotolithographic pattern are provided. The methods suitably comprise:(a) providing a substrate comprising one or more layers to be patternedover a surface of the substrate; (b) applying a layer of a photoresistcomposition of the invention over the one or more layers to bepatterned; (c) patternwise exposing the photoresist composition layer toactivating radiation; and (d) applying a developer to the photoresistcomposition layer to thereby produce a resist relief image. Suitably,the exposed photoresist composition layer is thermally treated in apost-exposure bake process prior to development.

In a preferred aspect, unexposed portions of the photoresist layer areremoved by the developer, leaving a photoresist pattern over the one ormore layer to be patterned. The patternwise exposing can be conducted byimmersion lithography or, alternatively, using dry exposure techniques.In certain aspects, implant and EUV lithography processes are alsopreferred.

Additional provided methods include forming a photolithographic pattern,comprising: (a) providing a substrate comprising one or more layers tobe patterned over a surface of the substrate; (b) applying a layer of aphotoresist composition over the one or more layers to be patterned; (c)applying a layer of a topcoat composition of the invention over or abovethe photoresist composition layer; (d) patternwise exposing both thetopcoat composition layer and the photoresist composition layer toactivating radiation; and (e) applying a developer to the imaged, coatedsubstrate to thereby produce a resist relief image. Suitably, theexposed photoresist composition and topcoat composition layers arethermally treated in a post-exposure bake process prior to development.In various aspects, patternwise exposing can be conducted by immersionlithography or, alternatively, using dry exposure techniques. In certainaspects, implant and EUV lithography processes are also preferred.

The invention also includes polymers that comprise a reactivenitrogen-containing moiety spaced from the polymer backbone, wherein thenitrogen-containing moiety produces a basic cleavage product duringlithographic processing of the photoresist composition.

Electronic devices formed by the disclosed methods are also provided.

Other aspects of the invention are disclosed infra.

DETAILED DESCRIPTION

Preferred additive compounds for use in photoresist and topcoatcompositions may be polymeric or non-polymeric, with non-polymericadditive compounds preferred for many applications. Preferred additivecompounds have relatively low molecular weight, for example, a molecularweight of less than or equal to 3000, more preferably ≤2500, ≤2000,≤1500, ≤1000, ≤800 or even more preferably ≤500.

Preferred additive compounds exhibit good solubility n orghanicphotoresist solcents such as ethyl lactate, propylene glycol methylether acetate (PGMEA), cyclohexanone and mixtures thereof.

In one aspect, preferred are additive compounds that comprise a blockedor masked acid group, such as an anhydride group.

Additive compounds useful in the present invention are generallycommercially available or can be readily synthesized. See, for instance,the examples which follow.

Photoresist and topcoat compositions of the invention suitably maycomprise one or more additive compounds in a wide amount range, such asfrom 0.005 to 20 wt. %, based on weight of total solids of thephotoresist or topcoat composition (total solids are all compositioncomponents except solvent), more preferably in amounts of 0.01, 0.05,0.1, 0.02, 0.3, 0.4, 0.5 or 1 to 1, 2, 3, 4, 5 or 10 wt % based on totalweight total solids of the composition and more typically amounts of0.01, 0.05, 0.1, 0.02, 0.3, 0.4, 0.05 or 1 to 5, 6, 7, 8, 9 or 10 weightpercent.

Specifically preferred additive compounds include the following:

In preferred compositions, the first polymer can migrate toward theupper surface of the resist coating layer during coating of thephotoresist composition. In certain systems, this can form a surfacelayer substantially made up of the first polymer. Without being bound byany theory, the nitrogen (basic) moiety of the first polymer is believedto contribute to the control of scattered or stray light, therebyallowing for reduction in patterning defects such as missing contactholes and micro-bridging defects in the case of line and trench patternformation. Following exposure and post exposure bake (PEB), the resistcoating layer can be developed, including in a developer comprising anorganic solvent. The organic developer removes unexposed regions of thephotoresist layer and the surface layer of the exposed regions. Benefitsof the inventive photoresist compositions can be achieved when using thecompositions in dry lithography or immersion lithography processes. Whenused in immersion lithography, preferred photoresist compositions canfurther exhibit reduced migration (leaching) of photoresist materialsinto an immersion fluid also a result of the additive polymer'smigration to the resist surface. Significantly, this can be achievedwithout use of a topcoat layer over the photoresist.

The photoresists can be used at a variety of radiation wavelengths, forexample, wavelengths of sub-400 nm, sub-300 or sub-200 nm, or with 248nm, 193 nm and EUV (e.g., 13.5 nm) exposure wavelengths being preferred.The compositions can further be used in electron beam (E-beam) exposureprocesses.

The photoresist compositions of the invention are preferablychemically-amplified materials. In preferred embodiments, thephotoresist compositions comprise one or more second or matrix polymers(distinct from the first polymer) that comprise an acid labile group.The acid labile group is a chemical moiety that readily undergoesdeprotection reaction in the presence of an acid. The second or matrixpolymer as part of a layer of the photoresist composition undergoes achange in solubility in a developer described herein as a result ofreaction with acid generated from the photoacid and/or thermal acidgenerator during lithographic processing, particularly followingsoftbake, exposure to activating radiation and post exposure bake. Thisresults from photoacid-induced cleavage of the acid labile group,causing a change in polarity of the second polymer. The acid labilegroup can be chosen, for example, from tertiary alkyl carbonates,tertiary alkyl esters, tertiary alkyl ethers, acetals and ketals.Preferably, the acid labile group is an ester group that contains atertiary non-cyclic alkyl carbon or a tertiary alicyclic carboncovalently linked to a carboxyl oxygen of an ester of the second matrixpolymer. The cleavage of such acid labile groups results in theformation of carboxylic acid groups. Suitable acid labile-groupcontaining units include, for example, acid-labile (alkyl)acrylateunits, such as t-butyl (meth)acrylate, 1-methylcyclopentyl(meth)acrylate, 1-ethylcyclopentyl (meth)acrylate,1-isopropylcyclopentyl (meth)acrylate, 1-propylcyclopentyl(meth)acrylate, 1-methylcyclohexyl (meth)acrylate, 1-ethylcyclohexyl(meth)acrylate, 1-isopropylcyclohexyl (meth)acrylate, 1-propylcyclohexyl(meth)acrylate, t-butyl methyladamantyl(meth)acrylate,ethylfenchyl(meth)acrylate, and the like, and other cyclic, includingalicyclic, and non-cyclic (alkyl) acrylates. Acetal and ketal acidlabile groups can be substituted for the hydrogen atom at the terminalof an alkali-soluble group such as a carboxyl group or hydroxyl group,so as to be bonded with an oxygen atom. When acid is generated, the acidcleaves the bond between the acetal or ketal group and the oxygen atomto which the acetal-type acid-dissociable, dissolution-inhibiting groupis bonded. Exemplary such acid labile groups are described, for example,in U.S. Pat. Nos. 6,057,083, 6,136,501 and 8,206,886 and European Pat.Pub. Nos. EP01008913A1 and EP00930542A1. Also suitable are acetal andketal groups as part of sugar derivative structures, the cleavage ofwhich would result in the formation of hydroxyl groups, for example,those described in U.S. Patent Application No. US2012/0064456A1.

For imaging at wavelengths of 200 nm or greater such as 248 nm, suitableresin materials (including for use as second polymers of the presentphotoresist compositions) include, for example, phenolic resins thatcontain acid-labile groups. Particularly preferred resins of this classinclude: (i) polymers that contain polymerized units of a vinyl phenoland an acid labile (alkyl) acrylate as described above, such as polymersdescribed in U.S. Pat. Nos. 6,042,997 and 5,492,793; (ii) polymers thatcontain polymerized units of a vinyl phenol, an optionally substitutedvinyl phenyl (e.g., styrene) that does not contain a hydroxy or carboxyring substituent, and an acid labile (alkyl) acrylate such as describedabove, such as polymers described in U.S. Pat. No. 6,042,997; (iii)polymers that contain repeat units that comprise an acetal or ketalmoiety that will react with photoacid, and optionally aromatic repeatunits such as phenyl or phenolic groups; such polymers described in U.S.Pat. Nos. 5,929,176 and 6,090,526, and blends of (i) and/or (ii) and/or(iii).

For imaging at certain sub-200 nm wavelengths such as 193 nm, the secondor matrix polymer is typically substantially free (e.g., less than 15mole %), preferably completely free, of phenyl, benzyl or other aromaticgroups where such groups are highly absorbing of the radiation. Suitablepolymers that are substantially or completely free of aromatic groupsare disclosed in European Patent Publication No. EP930542A1 and U.S.Pat. Nos. 6,692,888 and 6,680,159.

Other suitable second or matrix polymers include, for example, thosewhich contain polymerized units of a non-aromatic cyclic olefin(endocyclic double bond) such as an optionally substituted norbornene,for example, polymers described in U.S. Pat. Nos. 5,843,624 and6,048,664. Still other suitable matrix polymers include polymers thatcontain polymerized anhydride units, particularly polymerized maleicanhydride and/or itaconic anhydride units, such as disclosed in EuropeanPublished Application EP01008913A1 and U.S. Pat. No. 6,048,662.

Also suitable as the second or matrix polymer is a resin that containsrepeat units that contain a hetero atom, particularly oxygen and/orsulfur (but other than an anhydride, i.e., the unit does not contain aketo ring atom). The heteroalicyclic unit can be fused to the polymerbackbone, and can comprise a fused carbon alicyclic unit such asprovided by polymerization of a norbornene group and/or an anhydrideunit such as provided by polymerization of a maleic anhydride oritaconic anhydride. Such polymers are disclosed in International Pub.No. WO0186353A1 and U.S. Pat. No. 6,306,554. Other suitable hetero-atomgroup containing matrix polymers include polymers that containpolymerized carbocyclic aryl units substituted with one or morehetero-atom (e.g., oxygen or sulfur) containing groups, for example,hydroxy naphthyl groups, such as disclosed in U.S. Pat. No. 7,244,542.

In the case of sub-200 nm wavelengths such as 193 nm and EUV (e.g., 13.5nm), the second or matrix polymer may include a unit containing alactone moiety for controlling the dissolution rate of the second matrixpolymer and photoresist composition. Suitable monomers for use in thesecond or matrix polymer containing a lactone moiety include, forexample, the following:

Such a second or matrix polymer further typically includes a unitcontaining a polar group, which enhances etch resistance of the matrixpolymer and photoresist composition and provides additional means tocontrol the dissolution rate of the matrix polymer and photoresistcomposition. Monomers for forming such a unit include, for example, thefollowing:

The second or matrix polymer can include one or more additional units ofthe types described above. Typically, the additional units for thesecond or matrix polymer will include the same or similar polymerizablegroup as those used for the monomers used to form the other units of thepolymer, but may include other, different polymerizable groups in thesame polymer backbone.

In preferred aspects, the second or matrix polymer has a higher surfaceenergy than that of the first or additive polymer, described below, andshould be substantially non-miscible with the second polymer. As aresult of the difference in surface energies, segregation of the secondpolymer from the first polymer can take place during spin-coating. Asuitable surface energy of the second or matrix polymer is typicallyfrom 20 to 50 mN/m, preferably from 30 to 40 mN/m.

While not to be limited thereto, exemplary second or matrix polymersinclude, for example, the following:

As discussed, in preferred aspects, the second polymer may have halogensubstitution such as fluoro substitution, including fluoroalkyl, e.g.polymers that have hexofluoropropylalcohol substitution.

Suitable second or matrix polymers for use in the photoresistcompositions of the invention are commercially available and can readilybe made by persons skilled in the art. The second polymer is present inthe resist composition in an amount sufficient to render an exposedcoating layer of the resist developable in a suitable developersolution. Typically, the second polymer is present in the composition inan amount of from 50 to 95 wt % based on total solids of the resistcomposition. The weight average molecular weight M_(w) of the secondpolymer is typically less than 100,000, for example, from 3000 to100,000, more typically from 3000 to 15,000. Blends of two or more ofthe above-described second polymers can suitably be used in thephotoresist compositions of the invention.

The first or additive polymer is preferably a material that has a lowersurface energy than that of the second polymer and should besubstantially non-miscible with the second polymer. In this way,segregation or migration of the first polymer to the top or upperportions of an applied photoresist layer during the coating process isfacilitated. While the desired surface energy of the first polymer willdepend on the particular second polymer and its surface energy, thefirst polymer surface energy is typically from 18 to 40 mN/m, preferablyfrom 20 to 35 mN/m and more preferably from 29 to 33 mN/m. While thefirst polymer migrates to the upper surface of the resist layer duringthe coating process, it is preferable that there be some intermixingbetween the first polymer and second or matrix polymer immediatelybeneath the resist layer surface. Such intermixing is believed to aid inreducing surface inhibition in the resist layer by reduction orelimination of the acid generated in dark regions in the vicinity of thesecond or matrix polymer due to stray light. The extent of intermixingwill depend, for example, on the difference in surface energy (SE)between the second or matrix polymer (MP) and first or additive polymer(AP) (ΔSE=SE_(MP)−SE_(AP)). For given first or matrix and second oradditive polymers, the degree of intermixing can be increased withreduced ΔSE. The ΔSE is typically from 2 to 32 mN/m, preferably from 5to 15 mN/m.

As discussed, the first or additive polymers useful in the photoresistcompositions are copolymers that have a plurality of distinct repeatunits, for example, two, three or four distinct repeat units.

The first polymer is preferably free of silicon. Silicon-containingpolymers exhibit a significantly lower etch rate than organicphotoresist polymers in certain etchants. As a result, aggregation of asilicon-containing first polymer at the surface of an organic secondpolymer-based resist layer can cause cone defects during the etchingprocess. The first polymer may contain fluorine or can be free offluorine. Preferred first polymers are soluble in the same organicsolvent(s) used to formulate the photoresist composition. Preferredfirst polymers also will be soluble or become soluble upon post exposurebake (e.g., 120° C. for 60 seconds) in organic developers used innegative tone development processes.

As discussed, the first polymer preferably may contain a unit formedfrom one or more monomer corresponding to the following Formula (I):X₁—R₁—X₂—R₂—X₃  (I)wherein X₁ is a polymerizable functional group such as an acrylate oralkylacrylate such as a methacrylate; R₁ may be an optionallysubstituted linear, branched or cyclic aliphatic group or an aromaticgroup, suitably C₁₋₁₅ alkyl and optionally fluorinated; X₂ is a basicmoiety such as a nitrogen and may be a component of or taken togetherwith R₁ (e.g. R₁ and X₂ may combine to form a piperdinyl moiety); R₂ isan acid labile group; and X₃ may be optionally substituted linear,branched or cyclic aliphatic group or an aromatic group.

The polymerizable functional group X₁ can be chosen, for example, fromthe following general formulae (P-1), (P-2) and (P-3):

wherein R₂ is chosen from hydrogen, fluorine and fluorinated andnon-fluorinated C1 to C3 alkyl; and X is oxygen or sulfur;

wherein R₃ is chosen from hydrogen, fluorine and fluorinated andnon-fluorinated C1 to C3 alkyl; and

wherein m is an integer from 0 to 3.

Exemplary suitable monomers are described below, but are not limited tothese structures.

Preferably, the first polymer also comprises one or more additionaldistinct units (second units) formed from monomers corresponding to thefollowing general formula (I-1):

wherein: R₂ is chosen from hydrogen, fluorine and fluorinated andnon-fluorinated C1 to C3 alkyl; and X is oxygen or sulfur; and R₄ ischosen from substituted and unsubstituted C1 to C20 linear, branched andcyclic hydrocarbons, preferably fluorinated and non-fluorinated C1 toC15 alkyl, more preferably fluorinated and non-fluorinated C3 to C8alkyl and most preferably fluorinated and non-fluorinated C4 to C5alkyl, with R₄ preferably being branched to provide a higher waterreceding contact angle when used in immersion lithography, and R₄substitutions of haloalkyl and haloalcohol such as fluoroalkyl andfluoroalcohol being suitable.

As discussed, various moieties of monomers, polymers and other materialsmay be optionally substituted (or stated to be “substituted orunsubstituted”). A “substituted” substituent may be substituted at oneor more available positions, typically 1, 2, or 3 positions by one ormore suitable groups such as e.g. halogen (particularly F, Cl or Br);cyano; nitro; C₁₋₈ alkyl; C₁₋₈ alkoxy; C₁₋₈ alkylthio; C₁₋₈alkylsulfonyl; C₂₋₈ alkenyl; C₂₋₈ alkynyl; hydroxyl; nitro; alkanoylsuch as a C₁₋₆ alkanoyl e.g. acyl, haloalkyl particularly C₁₋₈ haloalkylsuch as CF₃; —CONHR, —CONRR′ where R and R′ are optionally substitutedC₁₋₈alkyl; —COOH, COC, >C═O; and the like.

Exemplary suitable monomers of Formula (I-1) are described below, butare not limited to these structures. For purposes of these structures,“R₂” and “X” are as defined above for Formula I-1.

Exemplary first polymers useful in the present photoresist compositionsinclude the following. For purposes of these structures, “R₂” and “X”are defined as follows: each R₂ is independently chosen from hydrogen,fluorine and fluorinated and non-fluorinated C1 to C3 alkyl; and each Xis independently oxygen or sulfur.

The photoresist compositions suitably include a single first polymer,but can optionally include one or more additional first polymers.Suitable polymers and monomers for use in the photoresist compositionsare commercially available and/or can readily be made by persons skilledin the art.

The first polymer is typically present in the photoresist composition ina relatively small amount, for example, in an amount of from 0.1 to 10wt %, preferably from 0.5 to 5 wt %, more preferably from 1 to 3 wt %,based on total solids of the photoresist composition. The content of thefirst or additive polymer will depend, for example, on the content ofacid generator in the photoresist layer, the content of thenitrogen-containing groups in the first polymer, and whether thelithography is a dry or immersion-type process. For example, the firstpolymer lower limit for immersion lithography is generally dictated bythe need to prevent leaching of the resist components. An excessivelyhigh first polymer content will typically result in pattern degradation.The weight average molecular weight of the additive polymer is typicallyless than 400,000, preferably from 3000 to 50,000, more preferably from3000 to 25,000. Suitable first polymers and monomers for making thefirst polymers for use in the photoresist compositions of the inventionare commercially available and/or can be made by persons skilled in theart.

The photosensitive composition preferably may comprise one or morephotoacid generators (PAG) employed in an amount sufficient to generatea latent image in a coating layer of the photoresist composition uponexposure to activating radiation. For example, the photoacid generatorwill suitably be present in an amount of from about 1 to 20 wt % basedon total solids of the photoresist composition. Typically, lesseramounts of the photoactive component will be suitable for chemicallyamplified resists.

A topcoat composition also may comprise one or more acid generatorcompounds, including one or more photoacid generator compound and/or oneor more thermal acid generator compounds. The PAGs disclosed herein andamounts thereof for use in a photoresist compositions are suitable for atopcoat composition. Relatively small amounts of a PAG is often suitablefor a topcoat composition.

Suitable PAGs are known in the art of chemically amplified photoresistsand include, for example: onium salts, for example, triphenylsulfoniumtrifluoromethanesulfonate, (p-tert-butoxyphenyl)diphenylsulfoniumtrifluoromethanesulfonate, tris(p-tert-butoxyphenyl)sulfoniumtrifluoromethanesulfonate, triphenylsulfonium p-toluenesulfonate,nitrobenzyl derivatives, for example, 2-nitrobenzyl p-toluenesulfonate,2,6-dinitrobenzyl p-toluenesulfonate, and 2,4-dinitrobenzylp-toluenesulfonate; sulfonic acid esters, for example,1,2,3-tris(methanesulfonyloxy)benzene,1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and1,2,3-tris(p-toluenesulfonyloxy)benzene; diazomethane derivatives, forexample, bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane; glyoxime derivatives, for example,bis-O-(p-toluenensulfonyl)-α-dimethylglyoxime, andbis-O-(n-butanesulfonyl)-α-dimethylglyoxime; sulfonic acid esterderivatives of an N-hydroxyimide compound, for example,N-hydroxysuccinimide methanesulfonic acid ester, N-hydroxysuccinimidetrifluoromethanesulfonic acid ester; and halogen-containing triazinecompounds, for example,2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, and2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine. One ormore of such PAGs can be used.

Suitable solvents for the photoresist and topcoat compositions of theinvention include, for example: glycol ethers such as 2-methoxyethylether (diglyme), ethylene glycol monomethyl ether, and propylene glycolmonomethyl ether; propylene glycol monomethyl ether acetate; lactatessuch as methyl lactate and ethyl lactate; propionates such as methylpropionate, ethyl propionate, ethyl ethoxy propionate andmethyl-2-hydroxy isobutyrate; Cellosolve esters such as methylCellosolve acetate; aromatic hydrocarbons such as toluene and xylene;and ketones such as methylethyl ketone, cyclohexanone and 2-heptanone. Ablend of solvents such as a blend of two, three or more of the solventsdescribed above also are suitable. The solvent is typically present inthe composition in an amount of from 90 to 99 wt %, more typically from95 to 98 wt %, based on the total weight of the photoresist composition.

Other optional additives for the photoresist compositions include, forexample, actinic and contrast dyes, anti-striation agents, plasticizers,speed enhancers, sensitizers, and the like. Such optional additives ifused are typically present in the composition in minor amounts such asfrom 0.1 to 10 wt % based on total solids of the photoresistcomposition, although fillers and dyes can be present in relativelylarge concentrations, for example, from 5 to 30 wt % based on totalsolids of the photoresist composition.

A preferred optional additive of resist compositions of the invention isan added base which can enhance resolution of a developed resist reliefimage. Suitable basic quenchers include, for example: linear and cyclicamides and derivatives thereof such asN,N-bis(2-hydroxyethyl)pivalamide, N,N-Diethylacetamide,N1,N1,N3,N3-tetrabutylmalonamide, 1-methylazepan-2-one,1-allylazepan-2-one and tert-butyl1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylcarbamate; aromatic aminessuch as pyridine, and di-tert-butyl pyridine; aliphatic amines such astriisopropanolamine, n-tert-butyldiethanolamine, tris(2-acetoxy-ethyl)amine, 2,2′,2″,2′″-(ethane-1,2-diylbis(azanetriyl))tetraethanol, and2-(dibutylamino)ethanol, 2,2′,2″-nitrilotriethanol; cyclic aliphaticamines such as 1-(tert-butoxycarbonyl)-4-hydroxypiperidine, tert-butyl1-pyrrolidinecarboxylate, tert-butyl 2-ethyl-1H-imidazole-1-carboxylate,di-tert-butyl piperazine-1,4-dicarboxylate and N (2-acetoxy-ethyl)morpholine. Of these basic quenchers,1-(tert-butoxycarbonyl)-4-hydroxypiperidine and triisopropanolamine arepreferred. The added base is suitably used in relatively small amounts,for example, from 1 to 20 wt % relative to the PAG, more typically from5 to 15 wt % relative to the PAG.

The photoresist and topcoat compositions can be used in accordance withthe invention are generally prepared following known procedures. Forexample, a resist of the invention can be prepared as a coatingcomposition by dissolving the components of the photoresist in asuitable solvent, for example, one or more of: a glycol ether such as2-methoxyethyl ether (diglyme), ethylene glycol monomethyl ether,propylene glycol monomethyl ether; propylene glycol monomethyl etheracetate; lactates such as ethyl lactate or methyl lactate, with ethyllactate being preferred; propionates, particularly methyl propionate,ethyl propionate and ethyl ethoxy propionate; a Cellosolve ester such asmethyl Cellosolve acetate; an aromatic hydrocarbon such toluene orxylene; or a ketone such as methylethyl ketone, cyclohexanone and2-heptanone. The desired total solids content of the photoresist willdepend on factors such as the particular polymers in the composition,final layer thickness and exposure wavelength. Typically the solidscontent of the photoresist varies from 1 to 10 wt %, more typically from2 to 5 wt %, based on the total weight of the photoresist composition.

The invention further provides methods for forming a photoresist reliefimage and producing an electronic device using photoresists of theinvention. The invention also provides novel articles of manufacturecomprising substrates coated with a photoresist composition of theinvention.

In lithographic processing, a photoresist composition may be applied ona variety of substrates. The substrate can be of a material such as asemiconductor, such as silicon or a compound semiconductor (e.g., III-Vor II-VI), glass, quartz, ceramic, copper and the like. Typically, thesubstrate is a semiconductor wafer, such as single crystal silicon orcompound semiconductor wafer, and may have one or more layers andpatterned features formed on a surface thereof. One or more layers to bepatterned may be provided over the substrate. Optionally, the underlyingbase substrate material itself may be patterned, for example, when it isdesired to form trenches in the substrate material. In the case ofpatterning the base substrate material itself, the pattern shall beconsidered to be formed in a layer of the substrate.

The layers may include, for example, one or more conductive layers suchas layers of aluminum, copper, molybdenum, tantalum, titanium, tungsten,alloys, nitrides or silicides of such metals, doped amorphous silicon ordoped polysilicon, one or more dielectric layers such as layers ofsilicon oxide, silicon nitride, silicon oxynitride, or metal oxides,semiconductor layers, such as single-crystal silicon, and combinationsthereof. The layers to be etched can be formed by various techniques,for example, chemical vapor deposition (CVD) such as plasma-enhancedCVD, low-pressure CVD or epitaxial growth, physical vapor deposition(PVD) such as sputtering or evaporation, or electroplating. Theparticular thickness of the one or more layers to be etched 102 willvary depending on the materials and particular devices being formed.

Depending on the particular layers to be etched, film thicknesses andphotolithographic materials and process to be used, it may be desired todispose over the layers a hard mask layer and/or a bottom antireflectivecoating (BARC) over which a photoresist layer is to be coated. Use of ahard mask layer may be desired, for example, with very thin resistlayers, where the layers to be etched require a significant etchingdepth, and/or where the particular etchant has poor resist selectivity.Where a hard mask layer is used, the resist patterns to be formed can betransferred to the hard mask layer which, in turn, can be used as a maskfor etching the underlying layers. Suitable hard mask materials andformation methods are known in the art. Typical materials include, forexample, tungsten, titanium, titanium nitride, titanium oxide, zirconiumoxide, aluminum oxide, aluminum oxynitride, hafnium oxide, amorphouscarbon, silicon oxynitride and silicon nitride. The hard mask layer caninclude a single layer or a plurality of layers of different materials.The hard mask layer can be formed, for example, by chemical or physicalvapor deposition techniques.

A bottom antireflective coating may be desirable where the substrateand/or underlying layers would otherwise reflect a significant amount ofincident radiation during photoresist exposure such that the quality ofthe formed pattern would be adversely affected. Such coatings canimprove depth-of-focus, exposure latitude, linewidth uniformity and CDcontrol. Antireflective coatings are typically used where the resist isexposed to deep ultraviolet light (300 nm or less), for example, KrFexcimer laser light (248 nm) or ArF excimer laser light (193 nm). Theantireflective coating can comprise a single layer or a plurality ofdifferent layers. Suitable antireflective materials and methods offormation are known in the art. Antireflective materials arecommercially available, for example, those sold under the AR™ trademarkby Rohm and Haas Electronic Materials LLC (Marlborough, MA USA), such asAR™40A and AR™124 antireflectant materials.

A photoresist layer formed from a composition of the invention asdescribed above is applied on the substrate. The photoresist compositionis typically applied to the substrate by spin-coating. Duringspin-coating, in resist compositions comprising both first and secondpolymers as disclosed herein, the first polymer in the photoresistsegregates to the upper surface of the formed resist layer typicallywith intermixing with the second polymer in regions immediately belowthe upper surface. The solids content of the coating solution can beadjusted to provide a desired film thickness based upon the specificcoating equipment utilized, the viscosity of the solution, the speed ofthe coating tool and the amount of time allowed for spinning A typicalthickness for the photoresist layer is from about 500 to 3000 Å.

The photoresist layer can next be softbaked to minimize the solventcontent in the layer, thereby forming a tack-free coating and improvingadhesion of the layer to the substrate. The softbake can be conducted ona hotplate or in an oven, with a hotplate being typical. The softbaketemperature and time will depend, for example, on the particularmaterial of the photoresist and thickness. Typical softbakes areconducted at a temperature of from about 90 to 150° C., and a time offrom about 30 to 90 seconds.

A topcoat composition can be utilized in accordance with knownprocedures and coated over an applied photoresist. See US20170090287 forprocedures using a topcoat composition which can be employed for thepresent topcoat compositions. Suitably, a top coat composition isutilized with an immersion exposure protocol.

The photoresist layer is next suitably exposed to activating radiationthrough a photomask to create a difference in solubility between exposedand unexposed regions. References herein to exposing a photoresistcomposition to radiation that is activating for the compositionindicates that the radiation is capable of forming a latent image in thephotoresist composition. The photomask has optically transparent andoptically opaque regions corresponding to regions of the resist layer toremain and be removed, respectively, in a subsequent development step.The exposure wavelength is typically sub-400 nm, sub-300 nm or sub-200nm, with 248 nm, 193 nm and EUV wavelengths being typical. Photoresistmaterials can further be used with electron beam exposure. The methodsfind use in immersion or dry (non-immersion) lithography techniques. Theexposure energy is typically from about 10 to 80 mJ/cm², dependent uponthe exposure tool and the components of the photosensitive composition.

Following exposure of the photoresist layer, a post-exposure bake (PEB)is performed. The PEB can be conducted, for example, on a hotplate or inan oven. Conditions for the PEB will depend, for example, on theparticular photoresist composition and layer thickness. The PEB istypically conducted at a temperature of from about 80 to 150° C., and atime of from about 30 to 90 seconds. A latent image defined by theboundary (dashed line) between polarity-switched and unswitched regions(corresponding to exposed and unexposed regions, respectively) is formedin the photoresist. The basic moiety (e g amine) of the first polymerdeprotected during the post-exppsire bake is believed to preventpolarity switch in dark regions of the photoresist layer where stray orscattered light may be present, resulting in a latent image withvertical walls. This is a result of neutralization of acid generated bythe PAG in the dark regions. As a result, cleavage of the acid-labilegroups in those regions can be substantially prevented.

The exposed photoresist layer is next developed suitably to removeunexposed regions of the photoresist layer. As discussed, the developermay be an organic developer, for example, a solvent chosen from ketones,esters, ethers, hydrocarbons, and mixtures thereof. Suitable ketonesolvents include, for example, acetone, 2-hexanone, 5-methyl-2-hexanone,2-heptanone, 4-heptanone, 1-octanone, 2-octanone, 1-nonanone,2-nonanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone,phenylacetone, methyl ethyl ketone and methyl isobutyl ketone. Suitableester solvents include, for example, methyl acetate, butyl acetate,ethyl acetate, isopropyl acetate, amyl acetate, propylene glycolmonomethyl ether acetate, ethylene glycol monoethyl ether acetate,diethylene glycol monobutyl ether acetate, diethylene glycol monoethylether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate,3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butylformate, propyl formate, ethyl lactate, butyl lactate and propyllactate. Suitable ether solvents include, for example, dioxane,tetrahydrofuran and glycol ether solvents, for example, ethylene glycolmonomethyl ether, propylene glycol monomethyl ether, ethylene glycolmonoethyl ether, propylene glycol monoethyl ether, diethylene glycolmonomethyl ether, triethylene glycol monoethyl ether and methoxymethylbutanol. Suitable amide solvents include, for example,N-methyl-2-pyrrolidone, N,N-dimethylacetamide and N,N-dimethylformamide.Suitable hydrocarbon solvents include, for example, aromatic hydrocarbonsolvents such as toluene and xylene. In addition, mixtures of thesesolvents, or one or more of the listed solvents mixed with a solventother than those described above or mixed with water can be used. Othersuitable solvents include those used in the photoresist composition. Thedeveloper is preferably 2-heptanone or a butyl acetate such as n-butylacetate.

Mixtures of organic solvents can be employed as a developer, forexample, a mixture of a first and second organic solvent. The firstorganic solvent can be chosen from hydroxy alkyl esters such asmethyl-2-hydroxyisobutyrate and ethyl lactate; and linear or branched C₅to C₆ alkoxy alkyl acetates such as propylene glycol monomethyl etheracetate (PGMEA). Of the first organic solvents, 2-heptanone and5-methyl-2-hexanone are preferred. The second organic solvent can bechosen from linear or branched unsubstituted C₆ to C₈ alkyl esters suchas n-butyl acetate, n-pentyl acetate, n-butyl propionate, n-hexylacetate, n-butyl butyrate and isobutyl butyrate; and linear or branchedC₈ to C₉ ketones such as 4-octanone, 2,5-dimethyl-4-hexanone and2,6-dimethyl-4-heptanone. Of the second organic solvents, n-butylacetate, n-butyl propionate and 2,6-dimethyl-4-heptanone are preferred.Preferred combinations of the first and second organic solvent include2-heptanone/n-butyl propionate, cyclohexanone/n-butyl propionate,PGMEA/n-butyl propionate, 5-methyl-2-hexanone/n-butyl propionate,2-heptanone/2,6-dimethyl-4-heptanone and 2-heptanone/n-butyl acetate. Ofthese, 2-heptanone/n-butyl acetate and 2-heptanone/n-butyl propionateare particularly preferred.

The organic solvents are typically present in the developer in acombined amount of from 90 wt % to 100 wt %, more typically greater than95 wt %, greater than 98 wt %, greater than 99 wt % or 100 wt %, basedon the total weight of the developer.

The developer also may be an aqueous alkaline composition such as a TMAHcomposition. Aqueous alkaline developers are commercially available.

The developer material may include optional additives, for example,surfactants such as described above with respect to the photoresist.Such optional additives typically will be present in minorconcentrations, for example, in amounts of from about 0.01 to 5 wt %based on the total weight of the developer.

The developer is typically applied to the substrate by spin-coating. Thedevelopment time is for a period effective to remove the unexposedregions of the photoresist, with a time of from 5 to 30 seconds beingtypical. Development is typically conducted at room temperature. Thedevelopment process can be conducted without use of a cleaning rinsefollowing development. In this regard, it has been found that thedevelopment process can result in a residue-free wafer surface renderingsuch extra rinse step unnecessary.

The BARC layer, if present, is selectively etched using resist patternas an etch mask, exposing the underlying hardmask layer. The hardmasklayer is next selectively etched, again using the resist pattern as anetch mask, resulting in patterned BARC and hardmask layers. Suitableetching techniques and chemistries for etching the BARC layer andhardmask layer are known in the art and will depend, for example, on theparticular materials of these layers. Dry-etching processes such asreactive ion etching are typical. The resist pattern and patterned BARClayer are next removed from the substrate using known techniques, forexample, oxygen plasma ashing.

The following non-limiting examples are illustrative of the invention.

EXAMPLES

Molecular Weight Determination:

In the following Examples, number and weight-average molecular weights,Mn and Mw, and polydispersity (PDI) values (Mw/Mn) for the polymers weremeasured by gel permeation chromatography (GPC) on a Waters alliancesystem equipped with a refractive index detector. Samples were dissolvedin HPLC grade THF at a concentration of approximately 1 mg/mL andinjected through four Shodex columns (KF805, KF804, KF803 and KF802). Aflow rate of 1 mL/min and temperature of 35° C. were maintained. Thecolumns were calibrated with narrow molecular weight PS standards(EasiCal PS-2, Polymer Laboratories, Inc.).

Examples 1-2: Resin Preparation

The following monomers were used to prepare fluorine-containing polymersB1 and B2 as described below.

Example 1: Polymer B1 Synthesis

A monomer feed solution was prepared by combining 139.5 g propyleneglycol monomethyl ether acetate (PGMEA), 150.0 g monomer M1, and 30.0 gmonomer M2. An initiator feed solution was prepared by combining 59.0 gPGMEA and 4.45 g V-601. The mixtures were agitated to dissolve thecomponents. 167.5 g PGMEA was introduced into a reaction vessel and thevessel was purged with nitrogen for 30 minutes. The reaction vessel wasnext heated to 80° C. with agitation. The monomer feed solution was thenintroduced into the reaction vessel and fed over a period of 2 hours,and the initiator feed solution was simultaneously fed into the reactionvessel over a period of 3 hours. The reaction vessel was maintained at80° C. for an additional seven hours with agitation, and was thenallowed to cool to room temperature. The reaction mixture was dilutedwith 500 mL tetrahydrofuran, then the polymer was precipitated bydropwise addition of the reaction mixture into 10 L of 4/1methanol/water (v/v). The solid polymer was collected by filtration, anddried in vacuo. Polymer B1 was obtained as a white solid powder [Yield:143 g, Mw=34.3 kDa, PDI=2.4].

Example 2: Polymer B2 Synthesis

A monomer feed solution was prepared by combining 89.1 g propyleneglycol monomethyl ether acetate (PGMEA), 188.0 g monomer M1, and 12.0 gmonomer M3. An initiator feed solution was prepared by combining 80.9 gPGMEA and 10.0 g V-601. The mixtures were agitated to dissolve thecomponents. 120.0 g PGMEA was introduced into a reaction vessel and thevessel was purged with nitrogen for 30 minutes. The reaction vessel wasnext heated to 90° C. with agitation. The monomer feed solution was thenintroduced into the reaction vessel and fed over a period of 2 hours,and the initiator feed solution was simultaneously fed into the reactionvessel over a period of 3 hours. The reaction vessel was maintained at90° C. for an additional seven hours with agitation, and was thenallowed to cool to room temperature. The reaction mixture was dilutedwith 500 mL tetrahydrofuran, then the polymer was precipitated bydropwise addition of the reaction mixture into 10 L of 4/1methanol/water (v/v). The solid polymer was collected by filtration, anddried in vacuo. Polymer B2 was obtained as a white solid powder [Yield:170 g, Mw=10.3 kDa, PDI=2.2].

Example 3: Photoresist Composition Preparation

Resist Components:

The following components were used to prepare resist compositions asdescribed in Table 1 below.

Resist Additives:

The following additives were used to prepare resist compositions asdescribed in Table 1.

Resist Composition Preparation:

Resist compositions were formulated by adding the components above to asolvent system comprising 1/1 by weight of propylene glycol monomethylether acetate (PGMEA) and methyl 2-hydroxybutyrate (HBM), in the amountsas described in Table 1. Each mixture was filtered through a 0.2 μm PTFEdisk.

TABLE 1 Example and comparative resist compositions. Example Polymer APolymer B PAG PAG PAG Q Additive C Solvent R1 A1 (100) B1 (4) PAG-1 (13)PAG-2 (3) PAG-3 (5) Q1 (0.5) C1 (0.1) S1 (3500) R2 A1 (100) B1 (4) PAG-1(13) PAG-2 (3) PAG-3 (5) Q1 (0.5) C2 (0.1) S1 (3500) R3 A1 (100) B1 (4)PAG-1 (13) PAG-2 (3) PAG-3 (5) Q1 (0.5) C3 (1) S1 (3500) R4 A1 (100) B1(4) PAG-1 (13) PAG-2 (3) PAG-3 (5) Q1 (0.5) C4 (0.1) S1 (3500) R5 A1(100) B2 (4) PAG-1 (13) PAG-2 (3) PAG-3 (5) Q1 (0.5) C1 (0.1) S1 (3500)R6 A1 (100) B2 (4) PAG-1 (13) PAG-2 (3) PAG-3 (5) Q1 (0.5) C2 (0.1) S1(3500) R7 A1 (100) B2 (4) PAG-1 (13) PAG-2 (3) PAG-3 (5) Q1 (0.5) C3(0.1) S1 (3500) R8 A1 (100) B2 (4) PAG-1 (13) PAG-2 (3) PAG-3 (5) Q1(0.5) C4 (0.1) S1 (3500) CR1 A1 (100) B1 (4) PAG-1 (13) PAG-2 (3) PAG-3(5) Q1 (0.5) S1 (3500) CR2 A1 (100) B1 (4) PAG-1 (13) PAG-2 (3) PAG-3(5) Q1 (0.5) CX1 (1) S1 (3500) CR3 A1 (100) B1 (4) PAG-1 (13) PAG-2 (3)PAG-3 (5) Q1 (0.5) CX2 (1) S1 (3500) CR4 A1 (100) B1 (4) PAG-1 (13)PAG-2 (3) PAG-3 (5) Q1 (0.5) CX3 (1) S1 (3500) CR5 A1 (100) B2 (4) PAG-1(13) PAG-2 (3) PAG-3 (5) Q1 (0.5) CX4 (1) S1 (3500) CR = comparativeexamples; S1 = 1/1 PGMEA/HBM.

Example 4: Resist Evaluations

NMR Experiments:

Resist compositions were stored at 35° C. for a specified time,whereupon they were diluted by half with d₆-acetone and ¹⁹F NMR spectrawere collected to determine the percent degradation offluorine-containing polymer B. This was done by comparing integrationsof fluorine peak corresponding to polymer and fluorine peakcorresponding to degradation product. ¹⁹F NMR spectra were acquired on aBruker AVANCE III HD 600 MHz spectrometer with a 5 mm SMARTProbe™ at 26°C. All NMR spectra are processed using MestReNova 6.2.1. Data from theanalysis is tabulated in Table 2.

TABLE 2 Degradation data from NMR analysis for example and comparativeresist compositions. % degradation % degradation % degradation ExampleWeek 0 Week 1 Week 2 BTFIB (R3) 0 0 0 Control (CR1) 1 8 12 BTIB (CR2) 110 14 Succinic (CR4) 1 4 10Shelf Life Stability Experiments:

Resist compositions were stored at 35° C. for a specified time,whereupon they were tested for receding contact angle and lithographicperformance.

Receding Contact Angle (RCA) Measurement:

On a TEL ACT-8 track, 200 mm silicon wafers were primed withhexamethyldisilazane (HMDS) at 120° C. for 30 seconds. Resistcompositions were coated to a thickness of 1,000 Å using a soft-bake of85° C. for 60 seconds. Receding water contact angles were measured usinga Kruss contact angle goniometer using deionized, Millipore filteredwater. For receding contact angle measurement, the droplet size of DIwater was 50 μl, and the wafer stage tilting rate was 1°/sec.

Lithographic Processing:

Resist compositions were evaluated by lithography as follows. A 200 mmwafer was first spin-coated with XU080538AA underlayer and baked at 240°C. for 60 seconds to form a 135 nm film. A SiARC was then spin-coated ontop and baked at 240° C. for 60 seconds to form a 22 nm film. Finally,the resist composition was spin-coated on top to form a 100 nm film andsoft baked at 85° C. for 60 seconds. The coated wafer was then exposedwith ArF excimer laser (193 nm) through a mask pattern having densespaces using an ArF exposure apparatus ASML-1100, NA=0.75 underconventional illumination. Thereafter, the wafer was baked at 95° C. for60 seconds followed by development with 0.26N aqueoustetramethylammonium hydroxide (TMAH) solution and subsequent water wash.Critical dimensions (CD) was determined by processing the image capturedby top-down scanning electron microscopy (SEM) using a Hitachi 9380CD-SEM, operating at an accelerating voltage of 800 volts (V), probecurrent of 8.0 picoampereres (pA), using 200K× magnification. A 100 nmdense trench was targeted with a mask CD of 100 nm and 200 nm pitch. 63sites were averaged for determination of CD.

TABLE 3 Performance data for example and comparative resistcompositions. RCA RCA RCA CD CD CD RCA Week 2/ Week 3/ Week 4/ CD Week2/ Week 3/ Week 4/ Example Week 0 35 C. 35 C. 35 C. Week 0 35 C. 35 C.35 C. PFP anhydride 92 90 92 92 93 91 (R1) HFB anhydride 92 91 90 94 9391 (R2) BTFIB (R3) 89 89 89 Koser (R4) 92 86 87 96 95 95 PFP anhydride90 89 89 91 91 89 (R5) HFB anhydride 88 87 88 91 91 90 (R6) BTFIB (R7)89 87 87 94 94 92 Koser (R8) 87 83 84 95 95 93 Control (CR1) 87 76 72 9797 95 BTIB (CR2) 76 71 Acetic (CR3) 89 79 Maleic anhydride 86 84 84 7694 97 96 (CR5)

Example 5: Topcoat Compositions

An overcoat or topcoat composition of the invention is prepared byadmixing the following components, 5.14 g polymer-B solution (20%) inIBIB, 2.21 g Quencher-A solution (1%) in IBIB and 92.7 g IBIB and thenthis mixture was filtered with a 0.2 micron Nylon filter.

Example 6: Immersion Lithography

300 mm HMDS-primed silicon wafers were spin-coated with ARTM26N (Rohmand Haas Electronic Materials) to form a first bottom anti-reflectivecoating (BARC) on a TEL CLEAN TRAC LITMUS i+, followed by the hakeprocess for 60 seconds at 205° C.

A coating layer of the photoresist composition of Example 3 (Resist R2)is spin coated over the BARC layer. The topcoat composition of Example 5is spin coated onto a silicon wafer having a coating layer of thephotoresist composition of Example 3 (Resist R2).

The fabricated films are then exposed through a mask on Nikon S306C ArFimmersion scanner using the illumination conditions as follows: 1.3 NA,Annular with XY-polarization, δ0.64-0.8 The exposure dose i varied from23.0 mJ/cm² to 47.0 mJ/cm² by 1 mJ/cm². The exposed film is thenpost-exposure baked at 90° C. for 60 seconds, followed by developingwith 0.26N TMAH aqueous developer.

What is claimed is:
 1. A photoresist composition, comprising: a firstmatrix polymer, wherein the first matrix polymer comprises an acidlabile group, but does not comprise fluorine; a second polymer distinctfrom the first polymer, wherein the second polymer comprises an acidlabile group, but is free of aromatic groups; one or more acidgenerators; and one or more additive compounds selected from


2. The photoresist composition of claim 1 wherein the second polymer isfluorinated.
 3. The photoresist composition of claim 1 wherein thesecond polymer comprises a repeat unit of the following Formula (3):

wherein in Formula (3), R₄ and R₅ are each independently a hydrogen, ahalogen, a C₁₋₈ alkyl, or C₁₋₈ haloalkyl group, and L is an optionallysubstituted multivalent linking group.
 4. The photoresist composition ofclaim 1, wherein the one or more additive compounds is:


5. The photoresist composition of claim 1, wherein the one or moreadditive compounds are selected:


6. A method for forming a photolithographic pattern, comprising: (a)applying a layer of a photoresist composition of claim 1 on a substrate;(b) patternwise exposing the photoresist composition layer to activatingradiation; and (c) developing the exposed photoresist composition layerto provide a photoresist relief image.
 7. A coated substrate,comprising: a topcoat composition, the topcoat composition comprising:(a) a first matrix polymer; (b) a second polymer distinct from the firstmatrix polymer; and (c) one or more additive compounds selected:

and a layer of a photoresist composition disposed on a substrate,wherein the topcoat composition is disposed on the layer of thephotoresist composition, wherein the topcoat composition and thephotoresist composition are different, and wherein the photoresistcomposition does not comprise the first matrix polymer or the secondmatrix polymer.
 8. The coated substrate of claim 7, wherein the secondpolymer is fluorinated.
 9. The coated substrate of claim 8, wherein thesecond polymer comprises a repeat unit of the following Formula (3):

wherein in Formula (3), R₄ and R₅ are each independently a hydrogen, ahalogen, a C₁₋₈ alkyl, or C₁₋₈ haloalkyl group, and L is an optionallysubstituted multivalent linking group.
 10. The coated substrate of claim7, where the topcoat composition comprises an additive comprising ananhydride.
 11. The coated substrate of claim 7, wherein the topcoatcomposition comprises an additive compound chosen from:


12. A method for forming a photolithographic pattern, comprising: (a)applying a layer of a photoresist composition on a substrate; (b) abovethe photoresist composition layer, applying a layer of a topcoatcomposition to form a topcoat layer; (c) patternwise exposing thephotoresist composition layer to activating radiation; and (d)developing the exposed photoresist composition layer to provide aphotoresist relief image, wherein the topcoat composition comprises: (a)a first matrix polymer; (b) a second polymer distinct from the firstmatrix polymer; and (c) one or more additive compounds selected from thegroup of:

wherein the topcoat composition and the photoresist composition aredifferent, and wherein the photoresist composition does not comprise thefirst matrix polymer or the second matrix polymer.
 13. A photoresistcomposition, comprising: a first matrix polymer, wherein the firstmatrix polymer comprises an acid labile group, but does not comprisefluorine; a second polymer distinct from the first polymer, wherein thesecond polymer comprises an acid labile group, but is free of aromaticgroups; one or more acid generators; and one or more additive compoundsselected:

wherein the second polymer comprises a repeat unit of the followingFormula (3):

wherein in Formula (3), R₄ and R₅ are each independently a hydrogen, ahalogen, a C₁₋₈ alkyl, or C₁₋₈ haloalkyl group, and L is an optionallysubstituted multivalent linking group.